Washington: Preparations are underway for the June 26 launch of the Interface Region Imaging Spectrograph (IRIS) to explore the Sun's lower atmosphere, or interface region, NASA said.

"The interface region, located between the Sun's visible surface and upper atmosphere, is where most of the Sun's ultraviolet emission is generated," NASA said in a statement.

The IRIS mission will be equipped with an ultraviolet telescope designed to capture images at short intervals. "Previous observations suggest there are structures in this region of the solar atmosphere 100 to 150 miles wide, but 100,000 miles long," Lockheed Martin IRIS principal investigator Alan Title said.

"Imagine giant jets like huge fountains that have a footprint the size of Los Angeles and are long enough and fast enough to circle Earth in 20 seconds. IRIS will provide our first high-resolution views of these structures along with information about their velocity, temperature and density," Title said.

The IRIS spacecraft was designed and built by Lockheed Martin's Advanced Technology Center in Palo Alto, California, and will be carried into space by an Orbital Sciences Corp. Pegasus XL rocket from Vandenberg Air Force Base on the central California coast.